Isovector spin susceptibility: Isotopic evolution of collectivity in spin response

Background: Response to spin-dependent operators has been investigated in the magnetic dipole and Gamow-Teller transitions, which provides properties of a nuclear system. Purpose: I investigate an isotopic dependence collectivity generated by interactions Ca Ni isotopes through isovector (IV) spin-flip excitations. The responses neutral $(t_z)$ charge-exchange $(t_{\pm})$ channels are considered unified way. Method: A energy-density functional approach is employed for calculating response functions based on Skyrme-Kohn-Sham-Bogoliubov method quasiparticle-random-phase approximation (QRPA). adopt like-particle QRPA proton-neutron channels, respectively. consider fluctuation pair fields. Results: collective shift due RPA correlations channel explained occupation probability neutrons $j_>=\ell+1/2$ orbital. Many particle-hole or two-quasiparticle excitations have coherent contribution form giant resonance neutron-rich nuclei channel. IV spin susceptibility displays evolution underlying shell structure. Conclusions: repulsive character residual interaction spin-isospin diminishes collectivity, while dynamic ${}^{3}S$ pairing appearing opposes reduction.